In aerospace applications, such apparatus as doors, missile launcher rotating devices and other mechanisms are held in engaged or locked condition by brake mechanisms which act against rotation of a rotatable drive member in the drive train for operating the apparatus. The brakes are disengaged to allow the related apparatus, such as a door or missile launcher rotating device, to be moved by the rotatable member. Conventionally, two separate brake assemblies are employed One brake assembly supplies system positional braking during operation and usually is hydraulically operated and released to hold the brake in disengaged condition. When on the ground or under other non-operational conditions, the hydraulic system normally is not activated. A second, manual brake assembly, independent of the hydraulic brake assembly, conventionally is employed for non-operational conditions. Alternatively, auxiliary or portable hydraulic brake units may be employed.
The second or manual brakes often are add-on units with no common components to the hydraulic system brake unit. Two separate assemblies, including brake plate sets, biasing springs, rotors and other components comprise the individual, differently operated brake units. Two braking systems create inefficient packaging, and an exhorbitant number of parts, increased costs and increased weight. These parameters are critical in aerospace applications.
In addition, it would be desirable for the manual brake to have the added function of performing a manual drive. However, such manual brake units must be able to counteract opposing and aiding loads on the output drive to prevent "run away". In other words, should the manual brake be used to attempt to hold the brake in disengaged condition, aiding or opposing loads such as a heavy door may be encountered, versus a manual force. The manual brake should be capable of effecting a controlled drive function allowing smooth operation and no run-away condition.
This invention is directed to providing a unitary, dual function brake and manual drive actuating system incorporating a hydraulic and a manual brake retracting means in a singular unit.